Wireless discovery of wireless device using one or more drones

ABSTRACT

An unmanned aerial vehicle may include a flight system, a wireless communication system, a processor, and a power system having a battery and a battery charging port. The power system may be operable to power the flight system, the wireless communication system, and the processor. The processor may be configured to operate the flight system to fly the unmanned aerial vehicle from a ground position to an in-air position while the battery charging port is attached to an air-to-ground tether, trigger a release of the air-to-ground tether from the battery charging port after determining the unmanned aerial vehicle has reached the in-air position and the battery is charged, and operate the flight system to execute a flight pattern while operating the wireless communication system to search for a wireless communication device.

FIELD

Embodiments described herein relate to systems and methods for locatinglost or missing individuals, and more particularly to searching forsignals from a user's electronic device with unmanned aerial vehicles.

BACKGROUND

Modern mobile devices such as mobile phones have myriad wirelesscommunication capabilities. For example, mobile phones may be able tocommunicate via cellular protocols, WiFi protocols, and the like.Further, users of such mobile devices often carry those devices withthem at all times, including when participating in outdoor activitiesand in locations where conventional land lines or other communicationsequipment is not widely available. Accordingly, mobile devices mayprovide essential communications and other capabilities to individualsin a variety of different environments and circumstances.

In parallel, unmanned aerial vehicle technology is becoming increasinglyeffective, safe, and affordable. Accordingly, unmanned aerial vehicles,such as small, multi-rotor vehicles sometimes referred to as “drones,”are becoming available for various novel and beneficial uses.

SUMMARY

This summary is provided to introduce a selection of concepts, insimplified form, that are further described in other sections. Thissummary is not intended to identify key features or essential featuresof the claimed subject matter, nor is it intended to be used as an aidin determining the scope of the claimed subject matter.

Described herein are unique systems and methods for using unmannedaerial vehicles (e.g., “drones”) to search for and locate individualswho may be lost, missing, or otherwise in need of assistance. Forexample, mobile phones, which people often carry at all times, may beconfigured to operate in a beacon mode where certain programs oroperations are suspended in order to increase battery life, and a beaconsignal is periodically transmitted by an antenna of the phone. Inconjunction, drones may be equipped with radios that can detect thebeacon signal, determine the location of the phone, and capture imagesof the location in question. The drones may fly along a flight patternin an area where the lost individual is likely to be in order to findthe individual. Unique charging techniques may also be used to maximizethe flight time of the drones, such as using releasable air-to-groundcharging tethers.

An unmanned aerial vehicle may include a flight system, a wirelesscommunication system, a processor, and a power system having a batteryand a battery charging port. The power system may be operable to powerthe flight system, the wireless communication system, and the processor.The processor may be configured to operate the flight system to fly theunmanned aerial vehicle from a ground position to an in-air positionwhile the battery charging port is attached to an air-to-ground tether,trigger a release of the air-to-ground tether from the battery chargingport after determining the unmanned aerial vehicle has reached thein-air position and the battery is charged, and operate the flightsystem to execute a flight pattern while operating the wirelesscommunication system to search for a wireless communication device.

The power system may be configured to receive power via theair-to-ground tether as the unmanned aerial vehicle moves from theground position to the in-air position. The power system may beconfigured to power the flight system using energy stored in the batteryto fly from the ground position to the in-air position, and theprocessor may be configured to at least partially recharge the batteryvia the air-to-ground tether before triggering the release of theair-to-ground tether.

The processor may be configured to search for the wireless communicationdevice by operating the wireless communication system to wirelesslyreceive, from the wireless communication device, an identifier of thewireless communication device, determining that the identifier matches asaved identifier, and wirelessly receiving, from the wirelesscommunication device, a location of the wireless communication device.

The unmanned aerial vehicle may further include a camera, and theprocessor may be configured to operate the flight system to fly theunmanned aerial vehicle to an in-air position proximate the location ofthe wireless communication device, and operate the camera to capture atleast one image of the location of the wireless communication device.

Operating the wireless communication system to wirelessly receive theidentifier of the wireless communication device may include operatingthe wireless communication system at a predetermined time and for apredetermined duration, and temporarily ceasing operation of thewireless communication system after the predetermined duration. Theprocessor may be configured to operate the wireless communication systemto request a data broadcast from the wireless communication device.

A wireless communication device may include a processor and a wirelesscommunication system including a first radio and a second radio. Thewireless communication device may also include a battery operable topower the wireless communication system and the processor. The processormay be configured to determine at least one of: that the wirelesscommunication system has not detected a cellular base station for apredetermined period of time, or that the battery has dropped below apredetermined charge level, and after making the determination, ceaseoperation of the first radio, operate the wireless communication systemto transmit, with the second radio, a series of signals, each respectivesignal being transmitted for a respective predetermined duration at arespective predetermined time, and between transmissions of the signals,cease operation of the second radio. The first radio may communicate viaa first frequency band, and the second radio may communicate via asecond frequency band that does not overlap with the first frequencyband.

The signals may include a signal set identifier (SSID). The signal mayinclude a unique device identifier associated with the wirelesscommunication device. The wireless communication device may furtherinclude a positioning system, and the signal may include a location ofthe wireless communication device as reported by the positioning system.The processor may be further configured to operate the wirelesscommunication system to transmit, with the second radio and in responseto a request from a remote unmanned aerial vehicle, a data broadcast.

A method for locating a device using an unmanned aerial vehicle mayinclude, at an unmanned aerial vehicle and during a flight of theunmanned aerial vehicle, at a first predetermined time and at a firstlocation, monitoring a radio spectrum for a wireless communicationsignal, in response to detecting the wireless communication signal,estimating a direction from the unmanned aerial vehicle to a source ofthe wireless communication signal, in response to not detecting thewireless communication signal, flying to a second location such that theunmanned aerial vehicle arrives at the second location at or before asecond predetermined time, and at the second predetermined time and atthe second location, monitoring the radio spectrum for the wirelesscommunication signal. The wireless communication signal may be a signalset identifier (SSID). The method may further include launching theunmanned aerial vehicle from a mobile launch apparatus.

The method may further include determining a location of a cellular basestation with which the device last communicated, moving the mobilelaunch apparatus to a launch location that is within a distance of thecellular base station, and after the mobile launch apparatus arrives atthe launch location, launching the unmanned aerial vehicle. The distancemay be about 50 miles or less.

The method may further include, after the mobile launch apparatusarrives at the launch location, launching one or more additionalunmanned aerial vehicles, each additional unmanned aerial vehicleconfigured to monitor the radio spectrum at the first predeterminedtime.

The method may further include, after launching the unmanned aerialvehicle, recharging a battery of the unmanned aerial vehicle bysupplying power to the unmanned aerial vehicle via an air-to-groundtether that is releasably coupled to the unmanned aerial vehicle, andafter recharging the battery to a target level, releasing theair-to-ground tether from the unmanned aerial vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements.

FIG. 1 illustrates an example scenario in which unmanned aerial vehicles(UAVs) are performing a search operation for a wireless communicationdevice.

FIGS. 2A-2C illustrate stages of an example UAV launching operation.

FIGS. 3A-3B illustrate example flight patterns of a UAV when searchingfor a signal from a wireless communication device.

FIGS. 4A-4B illustrate additional example flight patterns of a UAV whensearching for a signal from a wireless communication device.

FIGS. 5A-5B illustrate example flight altitudes for a UAV based ondifferent terrains.

FIGS. 6A-6B illustrate example operations for estimating a location of awireless communication device.

FIG. 7 is a flow chart of an example method for locating a wirelesscommunication device with a UAV.

FIG. 8 illustrates example components of a wireless communicationdevice.

FIG. 9 illustrates example components of a UAV.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following description is not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Mobile phones have become increasingly ubiquitous in modern society.These devices provide a wide range of functions and uses. For example,in addition to providing voice telephone services, they may also providetext messaging services, global positioning system (GPS) capabilities,wireless data communications (e.g., WiFi), and media playback functions,among numerous others. Further, users often keep their mobile phoneswith them at all times, and as such are rarely if ever without access towireless communications functions. In many cases, this allowsindividuals who find themselves in a predicament to seek assistance viatheir mobile phones. For example, a lost driver can easily access a mapto see their location and also find a route to an intended destination.However, should a user find himself or herself in a location wherewireless communications are unavailable, the mobile phone may be oflimited use. For example, if a hiker loses his or her way or becomesinjured in a remote location and cannot get cellular reception (e.g., aconnection to a cellular base station), they may not be able to call ormessage for help despite having their mobile phone with them. Further,if a user's phone is constantly searching for a connection to a cellularbase station, the device's battery may quickly become drained, renderingthe mobile phone essentially useless for communications or localizationfunctions. Accordingly, described herein are systems and techniques forusing a mobile phone to help find users who are lost or missing orotherwise in need, and who may not have cellular voice or dataconnectivity via their mobile phone.

In particular, a mobile phone may be operable in a beacon mode in which,under certain conditions, the device ceases trying to communicate to acellular base station (which may quickly drain the device's battery) andinstead sends a periodic signal (e.g., via a WiFi radio) that may bedetected by a nearby sensor and/or receiver. Because the user may be ina remote location and because WiFi signals from a mobile phone do nothave an infinite range, mobile search vehicles may be deployed to searchfor and locate the beacon, thereby locating the user. Due to theirmobility, versatility, size, range, and the like, the mobile searchvehicles may include unmanned aerial vehicles (UAVs), such asmulti-rotor UAVs, single-rotor helicopter-style UAVs, fixed wing UAVs,lighter-than-air UAVs (e.g., dirigibles, blimps, etc.), or any othersuitable type of UAV. Such UAVs may include onboard wirelesscommunications systems (e.g., antennas, radios, etc.) that search forbeacon signals from mobile devices as described above. Once a beacon ofa lost or missing person has been detected by the UAV, the UAV maydetermine a location of the user (or at least the user's device),capture images of an area where the user is believed to be, and relaythat information to other rescuers who may physically travel to the lostor missing user and render aid.

Various techniques are employed by a mobile phone and a UAV to improvethe likelihood of finding a user. For example, as noted above, when in abeacon mode, a mobile device may deactivate radios (and/or othercircuitry, applications, or operations) that cause rapid battery drain(e.g., cellular radios), and instead send out periodic signals via aradio that consumes less power to operate (e.g., a WiFi radio). Further,the mobile phone may transmit the beacon at a predetermined time and fora predetermined duration, and the one or more UAVs that are searchingfor the user may only activate their radios during the predeterminedtime and for the predetermined duration. As one specific example, abeacon mode may be configured to transmit a signal for twenty secondsevery twenty minutes, starting at the top of the hour (e.g., at 12:00,12:20, 12:40, 1:00, 1:20, and so on). Further, beacon modes may operateidentically across many instances of devices and UAVs, so thatregardless of what user is in need of assistance, which communicationdevice they are using, and which UAVs are searching for the user, theUAVs can always expect to find a beacon signal within the same timewindow. This may help to improve battery life of both the UAVs and themobile phones, as neither device needs to operate its radiocontinuously.

Other techniques may also be employed to increase the effectiveness ofthe system. For example, the UAVs may be launched from a mobile launchapparatus that conveys the UAVs to a location near a last-known locationof the user. Further, the mobile launch apparatus may include anair-to-ground tether that can recharge the batteries of the UAVs afterthe UAVs have been launched and have reached an in-air position. TheUAVs may release their tethers once the batteries are at least partiallyrecharged and/or reach a target charge value, so they can then freelyfly along a path to seek out the user. Other techniques and features aredescribed herein.

FIG. 1 illustrates an example scenario in which a fleet of UAVs 100 havebeen launched from a mobile launch apparatus 102 and are seeking awireless communication device 104 that has been reported to be lost,missing, or otherwise in need of assistance. The scene illustrated inFIG. 1 is of a user lost in a mountainous region, and optionally wherethe user is out of range of a cellular base station 106. Of course, thisparticular scene is merely for example purposes, and the operations,devices, techniques, etc. described with respect to FIG. 1 apply equallyor by analogy to other environments as well. For example, a UAV searchoperation may be used where a user is lost in a desert, at sea, in anurban environment, or the like.

As used herein, a wireless communication device 104 may be any suitabletype of wireless communication device that includes wirelesscommunication capabilities and/or communicates via wirelesscommunication protocols, such as cellular communications, WiFi,Bluetooth, IEEE 802.11, or the like. It will be understood that thewireless communication device may be a mobile phone, a tablet computer,a smart watch, a media player, or the like. Further, where the instantdiscussion refers to a particular type of wireless communication device(e.g., a mobile phone), it will be understood that other types ofdevices may in some cases be substituted for the mobile phone. UAVs(e.g., the UAVs 100) are depicted in the instant figures as multi-rotoraircraft, though this is merely for illustration, and any of theaforementioned types of UAVs may be substituted for the depictedmulti-rotor aircraft.

The wireless communication device 104 may be configured to operate in abeacon mode under certain circumstances, as described herein. A user maymanually activate the beacon mode, or the beacon mode may be initiatedby the device itself upon detection of certain conditions. For example,the device 104 may activate the beacon mode in response to determiningthat the device 104 is out of range of a cellular base station (e.g.,for a predetermined period of time, such as 30 minutes, one hour, or thelike), or that a cellular signal strength has dropped below a thresholdvalue. Additionally or alternatively, the device 104 may activate thebeacon mode in response to determining that the battery of the device104 has dropped below a predetermined charge level (e.g., 50%, 40%, 30%,20%, or any other suitable charge level).

When in the beacon mode, the wireless communication device 104 may turnoff or limit the operation of certain radios, antennas, applications,and/or other functions, in order to preserve the battery life of thewireless communication device 104 while in the beacon mode. For example,the wireless communication device 104 may cease operating one or morecellular radios (which may communicate via a first frequency band, suchas between about 800 MHz and about 2500 MHz). Additionally, in thebeacon mode the wireless communication device 104 may send a wirelesssignal via a WiFi communications protocol (e.g., an IEEE 802.11 basedprotocol, which may be a second frequency band that does not overlapwith the first frequency band, such as between about 2 GHz and about 5GHz). The beacon may correspond to a broadcast of a signal setidentifier (SSID), which is detectable by the wireless communicationsystem of the UAV. The SSID may include information about the wirelesscommunication device, such as a unique identifier of the device, alocation of the device (e.g., geographic coordinates from a GPS systemassociated with the device), a health status of the user (which may beselected by the user), a name or identity of the user, or the like. Insome cases, while the wireless communication device 104 is in the beaconmode, it periodically acquires a current location from a GPS systemassociated with the device, and updates the SSID to include the mostrecent GPS coordinates. When in the beacon mode, the device 104 mayoperate the GPS system less frequently as compared to a normal operatingmode, so as to further reduce the battery usage and thereby extend theoperational time of the beacon mode.

While the foregoing example describes the beacon signal as an SSID, anysuitable signal may be transmitted by the wireless communication devicewhen it is operating in a beacon mode. The content of the signal mayinclude any of the information described above, including an identifierof the wireless communication device, a name of the user, a periodicallyupdated GPS location, etc.

FIG. 1 illustrates a scenario in which the wireless communication device104 has been determined to be or reported lost or missing and, inresponse, the UAVs 100 have been launched from the mobile launchapparatus 102. As shown in FIG. 1, the mobile launch apparatus 102 isdepicted as a truck, though it may be any other suitable mobile launchapparatus such as a trailer, car, boat, or other powered or otherwisemovable vehicle or apparatus. The UAVs 100 are shown mid-flight,optionally after a recharging operation has taken place via anair-to-ground tether between the UAVs and the mobile launch apparatus102. The UAVs 100 may be flying along a flight pattern and periodicallyactivating its wireless communication system to monitor a radio spectrumto determine if they can detect a signal from the wireless communicationdevice 104 (as indicated by dotted lines 112). The UAVs 100 may monitora radio spectrum corresponding to the spectrum of the beacon signal fromthe wireless communication device 104. Upon detecting the signal fromthe wireless communication device 104 by a UAV 100, that UAV may performone or more operations. For example, the UAV 100 may determine orestimate a location of the wireless communication device 104, captureimages of an area where the signal was detected (optionally aftertravelling to a location that is estimated to be above the signalsource), alert other UAVs and/or a base station that the signal has beendetected (and optionally inform them of the location of the source, theidentity of the source, etc.), or the like.

The UAVs 100 may have been launched from a mobile launch apparatus 102,which may have traveled to a search area after a person had beenreported or otherwise determined to be missing or in need of help. Oncethe user is reported or determined to be missing or in need of help, anestimate of the user's last known location may be determined. Forexample, a location of a cellular base station 106 with which the devicelast communicated may be determined. More particularly, a searchoperation coordinator (which may be associated with or may communicatewith a wireless voice and data service provider) may be provided with anidentifier of the wireless communication device 104, and may determinewhich cellular base station 106 was most recently in communication withthe wireless communication device 104. Once the particular wireless basestation is identified, a search area or region may be determined basedat least in part on one or more properties of or associated with thecellular base station 106 and the wireless communication device 104. Forexample, a search radius or area around the location of the cellularbase station 106 may be based at least in part on the power of thecellular base station 106, a communication range of the cellular basestation 106, a last known direction to the wireless communication device104 from the cellular base station 106, or the like.

Once the last cellular base station 106 having been in communicationwith the wireless communication device 104 is identified, the mobilelaunch apparatus may be moved to a launch location that is within aparticular distance of the cellular base station 106. For example, themobile launch apparatus 102 may be moved to within a predetermineddistance (e.g., 1 mile, 10 miles, 50 miles) of the cellular base station106, or it may be moved to any location that is within a particular areasurrounding the base station, where the size and shape of the area (andthe particular location within the area) may depend at least in part onthe particular base station, the terrain around the base station, theavailability of roads or other traversable terrain near the basestation, etc. In other cases, the mobile launch apparatus 102 may bemoved to a location that is proximate (e.g., as close as is practicablegiven the terrain, roads, etc.) to a maximum effective range of thecellular base station 106, and optionally along a path that is betweenthe cellular base station 106 and the last known location of thewireless communication device 104 (e.g., along a straight line pathextending from the cellular base station 106 to the last known orestimated position/location of the wireless communication device 104).The location of or direction to the last known location of the wirelesscommunication device 104 may be determined using radio direction findingtechniques. In this way, the mobile launch apparatus 102 may bepositioned closer to the current location of the wireless communicationdevice 104 than would be achieved if the mobile launch apparatus 102were located directly at the cellular base station 106. Stateddifferently, because the wireless communication device 104 is known orbelieved to be out of range of the cellular base station 106, placingthe mobile launch apparatus 102 further away from the base station 106will likely result in the mobile launch apparatus 102 being closer tothe wireless communication device that is being sought.

Once the mobile launch apparatus 102 is positioned at the targetlocation, the UAVs 100 may be launched, optionally recharged afterreaching an in-air position, and sent along a flight pattern to searchfor the signal from the wireless communication device 104. The distanceof the mobile launch apparatus 102 to the cellular base station 106 maybe any suitable distance, such as about 1, 10, 20, 50, or 100 miles,though other distances are also contemplated.

FIGS. 2A-2C illustrate the mobile launch apparatus 102 at various stagesof an operation for launching and recharging UAVs 100. FIG. 2A shows twoUAVs 100 (though more or fewer UAVs may be included) on a launchplatform 200 of the mobile launch apparatus 102. As shown the launchplatform 200 is a bed of a truck, though it may take other forms as well(e.g., a bed of a trailer, a roof of a vehicle, a deck of a boat, theground, a fixed launch pad or location, etc.).

Each UAV 100 may include a flight system, a communication system, aprocessor, and a power system having a battery and a battery chargingport. The battery charging port of a UAV 100 may be attached to anair-to-ground tether 204 (FIG. 2B), which is configured to provide powerto the battery of the UAV 100, and may be released or decoupled from theUAV 100 to facilitate untethered flight of the UAV 100.

When the mobile launch apparatus 102 is at a launch location, the UAVsmay be launched to begin a search operation. In particular, all or asubset of the UAVs 100 may be commanded to fly from a ground position(e.g., on the launch platform 200) to an in-air position while thebattery charging ports of the UAVs 100 are releasably coupled to theirrespective air-to-ground tethers 204. FIG. 2B illustrates the mobilelaunch apparatus 102 and UAVs 100 after the UAVs 100 have reached theirin-air positions. In some cases, the in-air positions may correspond toa target altitude (e.g., above sea level or above ground) for a flightpattern for a search operation, and the UAVs 100 may attempt to maintainthis altitude to avoid unnecessary or undesirable power loss resultingfrom additional altitude changes. In other cases, the target altitude ofa flight pattern may differ from the in-air position of the UAVs 100during tethered charging.

When a UAV 100 is at or moving to the in-air position, power may beprovided to the UAV 100 through the air-to-ground tether 204. The powerprovided through an air-to-ground tether 204 may be used to recharge theonboard batteries of the attached UAV 100 during or after the travel tothe in-air position. For example, a UAV 100 may use energy stored in itsbatteries when flying to the in-air position. After (and/or while) theUAV 100 flies to the in-air position, power may be provided through theair-to-ground tether 204 to recharge the batteries of the UAV 100,thereby ensuring that the UAV 100 will have its maximum range availableto it for a search operation. In some cases, a UAV 100 may supply powerfrom the air-to-ground tether 204 directly to the motors of the UAV 100(and optionally all electrical components of the UAV 100) so that energyfrom the batteries is not used during the take-off operation.

After a UAV 100 has reached its in-air position and the batteries of theUAV 100 have reached or are at a target charge level (e.g., 100%charged, 90% charged, or any other suitable charge level), the UAV 100or the mobile launch apparatus 102 may trigger a release of theair-to-ground tether 204 from the battery charging port of the UAV 100.In cases where the UAV 100 uses only power from the air-to-ground tether204 to reach the in-air position, the air-to-ground tether 204 may bereleased as soon as the target in-air position is reached, withoutregard to the charge level of the battery. Triggering the release of theair-to-ground tether 204 may include causing a mechanism to mechanicallyunlatch or otherwise detach the air-to-ground tether 204 from the UAV100, and optionally forcefully eject or propel the air-to-ground tether204 away from the battery charging port and/or the UAV 100 (e.g.,towards the ground). FIG. 2C illustrates the UAVs 100 after havingreleased the air-to-ground tethers 204. After the air-to-ground tethers204 have been released, the UAVs 100 may operate their flight systems toexecute a flight pattern while operating their onboard wirelesscommunication systems to search for a wireless communication device, asdescribed herein.

The air-to-ground tethers 204 may be attached to take-up mechanisms 202(e.g., spools) that allow the air-to-ground tethers 204 to be paid outas the UAVs 100 ascend to their in-air position. Once the air-to-groundtethers 204 are detached from the UAVs 100 (e.g., after the UAVs 100have ascended to their in-air positions and optionally recharged to atarget level), the take-up mechanisms 202 may retract the air-to-groundtethers 204.

The air-to-ground tethers 204 may be coupled to a base power source thatprovides the electrical power for the UAVs 100. For example, theair-to-ground tethers 204 may be coupled to batteries, a generator(e.g., a gas or diesel powered generator), solar panels, a utility-levelpower source, or the like. The base power source may include powercontrollers and/or power conditioning components that provide the properpower to the UAVs 100 and control aspects of the charging and powersupply operations.

As described above, once a UAV 100 has been launched and has beenoptionally recharged using an air-to-ground tether, it may execute aflight pattern to search for a wireless communication device. The flightpattern may be selected so that the UAV is located at particular areasat particular times to increase the chances that the UAV will be withinrange of the wireless communication device at a time when the wirelesscommunication device is transmitting a beacon signal. In particular, theflight pattern may be based at least in part on an estimatedtransmission range of the wireless communication device and thetransmission time and transmission interval of the beacon. For example,if a wireless communication device is estimated to have a transmissionrange of one mile (e.g., defining a circle with a one mile radius), andtransmits a beacon for 20 seconds at 20 minute intervals (starting atthe top of each hour), a UAV should not travel more than about two milesbetween two of the 20 minute intervals because the UAV could potentiallyovershoot the location of the wireless communication device and miss abeacon.

FIG. 3A illustrates an example of a UAV travelling too far betweenbeacon times (e.g., the predetermined times at which the wirelesscommunication device is configured to emit a beacon signal). Inparticular, a UAV 300 (which may be an embodiment of a UAV 100) iswithin an area 302-1 at time T₀. The area 302-1 may correspond to anestimated range of transmission of a beacon transmitted by the wirelesscommunication device, and T₀ may correspond to the predetermined time atwhich the wireless communication device is configured to emit the beaconsignal. (The areas 302-1, 302-2, and 302-3 may each correspond to theestimated range of transmission of the wireless communication device.)If the UAV 300 overshoots the area 302-2 and is within the area 302-3 attime T₁, the UAV 300 could miss a transmission from a wirelesscommunication device within the area 302-2. Stated differently, if thewireless communication device were actually in the area 302-2, the UAV300 would likely not detect the beacon at time T₀ (because it is in thearea 302-1 and out of range of the area 302-2) and would also not detectthe beacon at time T₁ (because it is in the area 302-3 and is out ofrange of the area 302-2).

FIG. 3B illustrates an example of a flight pattern in which the maximumtravel distance of the UAV 300 between two adjacent beacon times isrestricted to a maximum distance D, based at least in part on theestimated transmission range of the wireless communication device inquestion. In particular, the UAV 300 is within the area 302-1 at timeT₀. The UAV 300 may fly along a path that results in the UAV 300 being adistance D (and optionally no greater than a distance D) away from itsinitial position at time T₁, thus placing the UAV 300 in area 302-2during the time when the wireless communication device is emitting theinstance of the beacon at T₁. The UAV 300 may continue according to thisscheme so that it does not fly out of range of a potential beaconlocation at a time when a beacon may be transmitted.

The transmission range (and thus the areas 302 and the maximum distanceD) may be based on various factors. For example, parameters andspecifications of the wireless device in question may be used whencalculating or determining the transmission range, such as a frequencyband (or bands) in which the beacon is being transmitted by that device,an antenna type or output power associated with the device, or the like(which may be known, for example, based on a cellular base stationhaving information about the device as a result of the lastcommunication between the cellular base station and the device). Otherfactors may also be considered, such as the terrain in which the user islocated, weather conditions, the sensitivity of the wirelesscommunication system of the UAV, and the like. Safety factors or otherscaling factors may also be applied (e.g., the distance D may beestablished as 80% of a calculated or theoretical range, or any othersuitable fraction of the calculated or theoretical range).

While FIGS. 3A-3B illustrate linear flight patterns, this is merely oneexample flight pattern, and the principles described above may applyequally or by analogy to other flight patterns as well. FIGS. 4A-4Billustrate example flight patterns of the UAV 300, in which the UAV 300is positioned no further than the distance D from its location at theprevious beacon time. FIG. 4A illustrates a linear path, similar tothose described with respect to FIGS. 3A-3B. In particular, the UAV 300may travel at a speed (e.g., D/|T₁−T₀|) that will result in the UAV 300arriving at the second listening location at or nearly at the time T₁,and arriving at the third listening location at the time T₂. FIG. 4Billustrates an example flight pattern in which the UAV 300 travels anonlinear path between adjacent listening locations, while still endingup, at T₀, no more than a distance D from the listening locationassociated with T₁ (and similarly, arriving, at T₂, a third listeninglocation no greater than a distance D away from the second listeninglocation).

In some cases, the UAV 300 does not actively search for the wirelesscommunication device between listening locations. This may help preservebattery power and allow the UAV to search a greater area. In othercases, the UAV 300 may actively search for the wireless communicationdevice between listening locations. For example, the UAV 300 may operateits wireless communication system to wirelessly receive beacon signals(if they are being transmitted) continuously during its flight. This mayincrease the chances of detecting a beacon from a device that isemitting beacons off schedule (e.g., due to a clock error of thewireless communication device).

Because the wireless communication device is configured to emit itsbeacon at a predetermined time and for a predetermined duration, the UAV300 may likewise operate its wireless communication system at the samepredetermined time and for the same predetermined duration (plus anoptional additional time buffer). The time at which the wirelesscommunication system is operated may correspond to or be associated withthe listening locations described above. In some cases, when thepredetermined time has passed (e.g., when no beacon is expected to beproduced), the UAV 300 may temporarily cease operation of its wirelesscommunication system at least until the next predetermined time (e.g.,when the next beacon is expected). This may help preserve the batteriesof the UAV 300, which may increase its maximum flight range and thusincrease the likelihood of finding the lost or missing individual.

The altitude at which a UAV flies during a search operation may bedetermined at least in part by the terrain over which the UAV is flying.For example, FIG. 5A illustrates an example in which a UAV 500 (whichmay be an embodiment of the UAV 100) is launched from a mobile launchapparatus 502 (which may be an embodiment of the mobile launch apparatus102) to fly a search operation over a substantially featureless terrain(e.g., a desert, field, body of water). In such cases, the UAV 500 mayfly at an altitude A₁, which may be higher than an altitude that wouldbe used if the UAV 500 were traversing a mountainous, hilly, or otherirregular terrain (as shown in FIG. 5B). Flying at the higher altitudemay allow the wireless communication system of the UAV 500 to have agreater effective range, as illustrated by the scanning area 504 in FIG.5A.

In contrast, FIG. 5B shows the UAV flying a search operation over amountainous terrain. In this case, the mountains (or other geologicstructures, foliage, etc.) may result in reduced effective communicationranges for the UAV 500 and a wireless communication device that the UAV500 is searching for. Accordingly, the UAV 500 may fly at a loweraltitude A₂ (as compared to A₁). The particular target altitude for aparticular drone and/or a particular search operation may be determinedin any suitable way, and may depend on factors such as an average groundfeature size across a search area. For example, if the average groundfeature size across a search area is 1000 feet or above (e.g., a searcharea with mountains of an average height of 1000 feet), the targetaltitude above the ground may be 100 feet, whereas if the average groundfeature size is 10 feet, the target altitude above the ground may be 300feet. The UAV 500 may attempt to maintain a constant altitude aboveground (e.g., it may follow the undulations of the terrain), or it mayattempt to maintain a constant altitude above sea level or anotherreference altitude (e.g., it may not change its altitude in response tochanges in the terrain).

During a search operation, such as those described above, a UAV may useits wireless communication system to attempt to detect the beacon from awireless communication device. As described herein, the beacon maycorrespond to a WiFi network (e.g., an IEEE 802.11 based network). Moreparticularly, the beacon may correspond to a broadcast of a signal setidentifier (SSID), which is detectable by the wireless communicationsystem of the UAV. The SSID may include information about the wirelesscommunication device, such as an identifier of the device, a location ofthe device (e.g., geographic coordinates from a GPS system associatedwith the device), a health status of the user (which may be selected bythe user), or the like.

When a UAV receives or detects the SSID, it may extract information fromthe SSID, such as the identifier of the device. The UAV may thendetermine if the received identifier matches a saved identifier toconfirm that the detected wireless communication device does, in fact,correspond to the device that the UAV is searching for. If the UAVdetermines that the received identifier does match the saved identifier,it may take further steps to aid in the search operation. For example,the UAV may alert other UAVs (and optionally a base station or searchoperation coordinator) that the signal has been detected. The UAV mayalso provide to the UAVs or search operation coordinator its ownlocation as well as any location information from the wirelesscommunication device itself (e.g., the geographic coordinates extractedfrom the SSID). As another example, the UAV may capture images (video orstill images) and optionally wirelessly send the images back to a UAVoperator or other individual or computer for storage and/or analysis.

The UAV may also communicate with the wireless communication device tocause the wireless communication device to perform certain additionaloperations. For example, the UAV may request that the wirelesscommunication device transmit a data broadcast that is different fromthe beacon. For example, the UAV may make a request that causes thewireless communication device to transmit a large amount of data (suchas a file, a pseudorandom noise signal, etc.) on multiple channels,frequencies, spectral bands, or the like. The signal corresponding tothis data broadcast may be more detectable by UAVs (e.g., detectable ata greater distance), and as such may help other nearby UAVs tocorroborate the location of the wireless communication device. However,it may use a relatively larger amount of battery power to emit such asignal, and therefore may be reserved until at least one UAV hasdetected the lower-power beacon signal and requested that the wirelesscommunication device emit the data broadcast.

In some cases, the beacon from a wireless communication device may notinclude the location of the wireless communication device, or it may bedesirable for the UAVs to attempt to independently determine thelocation of the wireless communication device, as the wirelesscommunication device may have been moved since its last GPS fix. UAVsmay determine or estimate the location of a wireless communicationdevice in various manners, examples of which are shown and describedwith respect to FIGS. 6A-6B.

FIG. 6A illustrates how a single UAV may determine the location of awireless communication device. In this instance, a UAV 600 (which may bean embodiment of the UAV 100) may detect a signal from a wirelesscommunication device 602. When the UAV 600 is at a first location 601,it may use one or more radio direction finding techniques to determine adirection from the UAV 600 to the wireless communication device 602(e.g., line 604). After the UAV 600 determines the direction from itsfirst location 601 to the wireless communication device 602, the UAV 600may move to a second location 605. The second location 605 may be apredetermined distance (e.g., 100 yards, 500 yards, or the like) along apredetermined direction (e.g., East, West), or it may be an arbitrarydistance, or it may be determined using other factors or considerations.Once the UAV 600 is at the second location, it may use one or more radiodirection finding techniques to determine a direction from the secondlocation 605 to the wireless communication device 602 (e.g., line 606).The UAV 600 may access or record its own location (e.g., from an onboardGPS system) when it is determining the direction to the wirelesscommunication device 602. Accordingly, the UAV 600 (or another deviceassociated with the UAV 600) can use the first and second locations ofthe UAV 600 and the first and second directions to the wirelesscommunication device 602 to triangulate the location of the wirelesscommunication device 602. Once the location of the wirelesscommunication device 602 has been determined, the UAV 600 may informother UAVs, a base station, a search operation coordinator, or the like,of the location of the wireless communication device 602.

FIG. 6B illustrates how multiple UAVs may be used to determine thelocation of the wireless communication device 602. In this case, insteadof a single UAV 600, multiple UAVs each independently determine theirrespective directions to the wireless communication device 602. Forexample, as shown in FIG. 6B, three UAVs (UAV 600-1, 600-2, and 600-3)each determine a direction from their respective locations to thewireless communication device 602 (e.g., indicated by lines 608, 610,612). These directions along with the locations of each of the UAVs maybe shared with each other, with a master or primary UAV (e.g., the UAV600-1), and/or a base station or other search operation coordinator,which may then in turn use the locations of the UAVs and the directionsto the wireless communication device 602 to triangulate the location ofthe wireless communication device 602.

After the location of a wireless communication device (e.g., thewireless communication device 602) is determined or estimated, one ormore UAVs may fly to an in-air position that is proximate the locationof the wireless communication device, and once at the in-air position,capture at least one image of the location of the wireless communicationdevice. The one or more images may be still or video images. Further,the image may capture visible light (with or without external lightsources such as flashes, spotlights, or the like), or infrared light(with or without external infrared light sources). Images captured bythe UAVs may be transmitted wirelessly to other UAVs, a base station, asearch operation coordinator, or the like, to assist in physicallylocating the lost or missing user. In some cases, the images areassociated with location information, such as a location of the UAV whenthe image was captured, the estimated location of the wirelesscommunication device, the identifier of the wireless communicationdevice, or the like.

FIG. 7 is a flow chart of an example method 700 for locating a wirelesscommunication device using a UAV. At operation 702, while a UAV isexecuting a flight pattern such as that described with respect to FIGS.4A-4B, the UAV may monitor a radio spectrum for a wireless communicationsignal (e.g., a beacon from a wireless communication device) when theUAV is at a first predetermined time (e.g., Time T₀ in FIG. 4A or 4B)and when the UAV is at a first location. The radio spectrum maycorrespond to the radio spectrum on which the beacon is transmitted.

At operation 704, in response to detecting the wireless communicationsignal, the UAV may estimate a direction from the UAV to a source of thewireless communication signal. For example, the UAV may use radiodirection finding techniques to estimate a direction to the source ofthe signal.

At operation 706, in response to not detecting the wirelesscommunication signal at the first location and at the firstpredetermined time, the UAV may fly to a second location such that theunmanned aerial vehicle arrives at the second location at or before asecond predetermined time (e.g., time T₁ in FIG. 4A or 4B). At operation708, once the UAV is at the second location, and at the secondpredetermined time, the UAV may once again monitor the radio spectrumfor the wireless communication signal. In response to detecting thewireless communication signal at the second location and at the secondpredetermined time, the UAV may estimate a direction from the UAV to thesource of the wireless communication signal, as described above.

In any instance when a UAV detects the wireless communication signal,the UAV may perform additional operations, such as communicating withthe wireless communication device to provide information to the wirelesscommunication device (e.g., acknowledging that the user has been found,providing instructions to stay in one place or to move to anotherlocation, supplying a map or other physical directions, providing anestimated rescue time, or the like). The UAV may also travel to andcapture images of an estimated location of the source of the wirelesscommunication signal. The UAV may also send information to other UAVsand/or a base station or search operation coordinator, such as thelocation of the user, images captured of the location of the user, andthe like.

FIG. 8 depicts an example schematic diagram of a wireless communicationdevice 800. By way of example, the device 800 of FIG. 8 may correspondto the wireless communication device 104 shown in FIG. 1 (or any otherwireless communication device described herein). To the extent thatmultiple functionalities, operations, and structures are disclosed asbeing part of, incorporated into, or performed by the device 800, itshould be understood that various embodiments may omit any or all suchdescribed functionalities, operations, and structures. Thus, differentembodiments of the device 800 may have some, none, or all of the variouscapabilities, apparatuses, physical features, modes, and operatingparameters discussed herein.

As shown in FIG. 8, a device 800 includes a processing unit 802 that mayinclude one or more processors and memory units. The processing unit 802may be configured to receive signals from various components and systemsof the device 800, and provide control signals to such components andsystems based on programs run on the processors.

The device 800 may also include a power system 801, which may includeone or more batteries, charging components, power controllers, or othersuitable components or systems for providing power to the device 800. Asdescribed herein, the power system 801 may communicate with or provideinformation to a beacon system, which may in turn determine how and whento operate a beacon system (including when to deactivate cellular orother radios or communications systems).

The device 800 may also include a communication system 804. Thecommunication system 804 may include antennas, radios, controllers,signal processing components, or other suitable components or systemsthat facilitate communication with other devices. For example, thecommunication system 804 may include radios and associated antennas forcommunicating via multiple different wireless communication protocols.More particularly, the communication system 804 may include radios andantennas for cellular communications (e.g., using any suitable cellulartechnology or communications protocol, including but not limited to 2G,3G, 4G, 5G, LTE, CDMA, TDMA, GSM, GPRS, and so forth). The communicationsystem 804 may also include radios and antennas for other wirelessprotocols, such as WiFi (e.g., IEEE 802.11 protocols, including forexample 2.4 GHz protocols, 5 GHz protocols, etc.), Bluetooth, and soforth.

The device 800 may also include a beacon system 806. The beacon system806 may communicate with and optionally control aspects of thecommunication system 804 and the power system 801 to perform operationsas described herein. For example, the beacon system 806 may monitor thestate of charge of one or more batteries associated with the powersystem 801, and upon detecting certain conditions (e.g., state of chargethresholds, cellular connectivity), cease operation of some portions ofthe communication system 804 (e.g., cellular radios and antennas), andoperate others (e.g., WiFi radios and antennas) in a beacon mode. Insome cases, the beacon system 806 selects an available WiFi protocol orband that has the greatest range and/or ability to penetrate obstacles.For example, where both 2.4 GHz and 5 GHz radios and antennas areavailable, the beacon system 806 may choose to operate the beacon on the2.4 GHz spectrum.

FIG. 9 depicts an example schematic diagram of a UAV 900. By way ofexample, the UAV 900 of FIG. 9 may correspond to the UAV 100 shown inFIG. 1 (or any other UAV described herein). To the extent that multiplefunctionalities, operations, and structures are disclosed as being partof, incorporated into, or performed by the UAV 900, it should beunderstood that various embodiments may omit any or all such describedfunctionalities, operations, and structures. Thus, different embodimentsof the UAV 900 may have some, none, or all of the various capabilities,apparatuses, physical features, modes, and operating parametersdiscussed herein.

As shown in FIG. 9, a UAV 900 includes a processing unit 902 that mayinclude one or more processors and memory units. The processing unit 902may be configured to receive signals from various components and systemsof the UAV 900, and provide control signals to such components andsystems based on programs run on the processors.

The UAV 900 may also include an onboard power system 901, which mayinclude one or more batteries, charging components, power controllers,or other suitable components or systems for providing power to the UAV900. As described herein, the onboard power system 901 may be configuredto receive power from an air-to-ground tether, and charge the batteriesof the onboard power system 901 and/or provide power directly from theair-to-ground tether to other components of the UAV 900, such as motorsor other propulsion systems.

The UAV 900 may also include a communication system 904. Thecommunication system 904 may include antennas, radios, controllers,signal processing components, or other suitable components or systemsthat facilitate communication with other devices. For example, thecommunication system 904 may include radios and associated antennas forcommunicating via multiple different wireless communication protocols.More particularly, the communication system 904 may include radios andantennas for cellular communications (e.g., using any suitable cellulartechnology or communications protocol, including but not limited to 2G,3G, 4G, 5G, LTE, CDMA, TDMA, GSM, GPRS, and so forth). The communicationsystem 904 may also include radios and antennas for other wirelessprotocols, such as WiFi (e.g., IEEE 802.11 protocols, including forexample 2.4 GHz signals, 5 GHz signals), Bluetooth, and so forth. Insome cases, the UAV 900 includes one or more directional antennas thatmay be utilized during a search operation to determine a directionbetween the UAV and a wireless communication device, as described above.In some cases, the UAV 900 also or instead includes a non-directionalantenna. In some cases, the UAV 900 operates its non-directional antennawhen monitoring a radio spectrum for a wireless communication signal,and operates its directional antenna after detecting the wirelesscommunication signal to estimate the direction from the UAV 900 to thesource of the wireless communication signal. In some cases the UAV 900includes multiple directional antennas, which when operated inconjunction with one another provide wireless coverage similar to thatof a non-directional antenna, while also providing direction-findingfunctionality using the same antennas (or a subset of the antennas).

The communication system 904 may also receive instructions from a remoteoperator (e.g., a human or computerized operator). Such instructions mayinclude manual flight control instructions (e.g., from a remote controldevice), commands to initiate predetermined flight patterns or otherflight or UAV control sequences (e.g., a launch and charge sequence, aflight pattern, a return-to-base sequence), or the like.

The UAV 900 may include a flight system 906 that controls flightoperations of the UAV 900, and may include, control, or interface withflight hardware, such as motors, propellers, flight control surfaces,and the like. The flight system 906 may receive global positioningsystem (GPS) signals as part of controlling the flight operations of theUAV 900. The flight system 906 may receive control signals from theprocessing unit 902 to perform specific flight operations, such aslaunch or landing operations (FIGS. 2A-2C), flight patterns (e.g., FIGS.4A-5B), location finding sequences (e.g., FIGS. 6A-6B).

The UAV 900 may include a camera system 908. The camera system 908 mayinclude lenses, image sensors, light sources (e.g., flashes, floodlights, or other illumination components), or the like. The camerasystem 908 may capture video or still images (or both), and may captureimages based on visible light, infrared light, or both.

Other examples and implementations are within the scope and spirit ofthe disclosure and appended claims. For example, features implementingfunctions may also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. Also, as used herein, including in theclaims, “or” as used in a list of items prefaced by “at least one of”indicates a disjunctive list such that, for example, a list of “at leastone of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., Aand B and C). Further, the term “exemplary” does not mean that thedescribed example is preferred or better than other examples.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not targeted to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. An unmanned aerial vehicle, comprising: a flightsystem; a wireless communication system; a processor; and a power systemhaving a battery and a battery charging port; wherein: the power systemis operable to power the flight system, the wireless communicationsystem, and the processor; and the processor is configured to: operatethe flight system during a take-off operation to fly the unmanned aerialvehicle from a ground position to an in-air position while the batterycharging port is attached to a detachable air-to-ground tether, theground position at a first altitude and the in-air position at a secondaltitude higher than the first altitude; determine the unmanned aerialvehicle has reached the in-air position; operate the power system torecharge the battery, via the battery charging port and the detachableair-to-ground tether, while ascending in altitude from the firstaltitude to the second altitude or while hovering at the secondaltitude; trigger a release of the detachable air-to-ground tether fromthe battery charging port and the unmanned aerial vehicle afterdetermining the unmanned aerial vehicle has reached the in-air positionand after determining the battery is recharged; and operate the flightsystem to execute a flight pattern while operating the wirelesscommunication system to search for a wireless communication device. 2.The unmanned aerial vehicle of claim 1, wherein the power system isconfigured to receive power via the battery charging port and theair-to-ground tether as the unmanned aerial vehicle moves from theground position to the in-air position during the take-off operation. 3.The unmanned aerial vehicle of claim 1, wherein: the power system isconfigured to power the flight system using energy stored in the batteryto fly from the ground position to the in-air position; and theprocessor is configured to at least partially recharge the battery viathe battery charging port and the air-to-ground tether before triggeringthe release of the air-to-ground tether.
 4. The unmanned aerial vehicleof claim 1, wherein: the processor is configured to search for thewireless communication device by: operating the wireless communicationsystem to wirelessly receive, from the wireless communication device, anidentifier of the wireless communication device; determining that theidentifier matches a saved identifier; and wirelessly receiving, fromthe wireless communication device, a location of the wirelesscommunication device.
 5. The unmanned aerial vehicle of claim 4, furthercomprising: a camera; wherein: the processor is configured to: operatethe flight system to fly the unmanned aerial vehicle to an in-airposition proximate the location of the wireless communication device;and operate the camera to capture at least one image of the location ofthe wireless communication device.
 6. The unmanned aerial vehicle ofclaim 4, wherein operating the wireless communication system towirelessly receive the identifier of the wireless communication deviceincludes: operating the wireless communication system at a predeterminedtime and for a predetermined duration; and temporarily ceasing operationof the wireless communication system after the predetermined duration.7. The unmanned aerial vehicle of claim 4, wherein the processor isconfigured to operate the wireless communication system to request adata broadcast from the wireless communication device.
 8. A method forlocating a device using an unmanned aerial vehicle, comprising: at theunmanned aerial vehicle: taking off from a launch platform, at a firstaltitude, while connected to a remote power source via a detachableair-to-ground tether; determining the unmanned aerial vehicle hasreached an in-air position at a second altitude; recharging a battery ofthe unmanned aerial vehicle, while the unmanned aerial vehicle is at thein-air position, by receiving power via the detachable air-to-groundtether; and triggering a release of the detachable air-to-ground tetherfrom the unmanned aerial vehicle after determining the unmanned aerialvehicle has reached the in-air position and after determining thebattery is recharged; and at the unmanned aerial vehicle and during aflight of the unmanned aerial vehicle: at a predetermined time,monitoring a radio spectrum for a wireless communication signal;detecting the wireless communication signal; and in response todetecting the wireless communication signal, estimating a direction fromthe unmanned aerial vehicle to a wireless communication device.
 9. Themethod of claim 8, wherein the wireless communication signal is a signalset identifier (SSID).
 10. The method of claim 8, wherein the launchplatform is on a mobile launch apparatus.
 11. A method for operating anunmanned aerial vehicle, comprising: at the unmanned aerial vehicle:taking off from a launch platform, at a first altitude, while connectedto a remote power source via a detachable air-to-ground tether;determining the unmanned aerial vehicle has reached an in-air positionat a second altitude higher than the first altitude; recharging abattery of the unmanned aerial vehicle, while the unmanned aerialvehicle is at the in-air position, by receiving power via the detachableair-to-ground tether; and triggering a release of the detachableair-to-ground tether from the unmanned aerial vehicle after, determiningthe unmanned aerial vehicle has reached the in-air position; anddetermining the battery is recharged.
 12. The method of claim 11,further comprising: recharging the battery of the unmanned aerialvehicle, by receiving power via the detachable air-to-ground tether,while the unmanned aerial vehicle is ascending from the first altitudeto the second altitude.
 13. The method of claim 11, further comprising:ascending from the first altitude to the second altitude without theunmanned aerial vehicle receiving power via the detachable air-to-groundtether; and powering the unmanned aerial vehicle using energy stored inthe battery while ascending from the first altitude to the secondaltitude.
 14. The method of claim 11, wherein determining the battery isrecharged comprises determining the battery is recharged to 100%capacity.
 15. The method of claim 11, wherein determining the battery isrecharged comprises determining the batter is recharged to at least 90%capacity.
 16. The method of claim 11, further comprising: operating aflight system of the unmanned aerial vehicle to execute a flight patternwhile operating a wireless communication system of the unmanned aerialvehicle to search for a wireless communication device.
 17. The method ofclaim 11, wherein the launch platform is on the ground.
 18. The methodof claim 11, wherein the launch platform is on a mobile launchapparatus.